The present invention relates to a system for determining a proportion of foreign bodies in relation to fruit. The invention has particular application to the determination of a percentage of leaves and branches in a batch of fruit, berries and the like which have been harvested or of fruit, berries and the like grown on fruit trees or bushes. A particular application of this invention relates to the field of machines for harvesting fruit, berries and the like produced on fruit trees or bushes grown in rows. Such a machine comprises a high clearance chassis which can be travelled over fields and one or more shaker assemblies mounted on the chassis. The shaker assembly comprises one or more pairs of elongated shaker units which extend approximately horizontally in the direction of one of the longitudinal median axes of the machine.
The shaker units are spaced transversely to each other on either side of the longitudinal median axis. The shaker assembly also comprises a control mechanism connected to the shaker units to activate them in a synchronized reciprocating movement in a transverse direction in relation to the longitudinal median axis.
The invention will be described in relation to a particular example relating to the harvesting of grapes. However, it will be appreciated that the invention is also applicable to the harvesting of other fruits and berries, for example, black currants, gooseberries, raspberries and, more generally, to the harvesting of any fruit grown on trees or bushes planted in rows.
The principle of harvesting grapes is practically the same for most known grape harvesting machines. It involves shaking the vine by applying a sinusoidal, pseudosinusoidal or similar movement of the proper amplitude and frequency to detach the grapes or bunches of grapes. The movement is transmitted upon the vine by shaker units spaced so that they act either on the stock or vine or on the vegetation, that is, the fruiting area, depending on the type and number of shaker units used. The percentage of bunches and/or grape berries detached from the vine depends on the number and amplitude of the oscillations to which a given bunch of grapes is subjected. The more energetically and the more times a bunch is shaken, the more chance there is of said bunch or its individual grapes being detached from the vine. The number and amplitude of the oscillations to which a given bunch is subjected in turn depend essentially on various parameters which can be selected, particularly the amplitude and frequency of the control mechanism connected to the shaker units and the forward speed of the machine.
In detaching the bunches or grapes, the shaker units can also cause substantial detachment of leaves and/or breakage of shoots and/or buds. Apart from the fact that such damage compromises the future yield of the vine, the foreign bodies thus collected with the grapes cause problems with cleaning the crop which may lead to oenological problems.
The more energetically and the more times the shaker units act on the vine vegetation, the more and greater the above-mentioned damage will be. It is therefore normally necessary to find a compromise between the various above-mentioned parameters in order to obtain an acceptable percentage of harvested bunches or grapes without causing too much damage to the vine or complicating the cleaning of the crop.
Up to now, the working parameters of the harvester has been set manually by the driver based on visual observation of the harvest or of the vine plants after the machine has passed over them. Even though certain parameters such as shaker frequency can be adjusted from the driver's seat, such a visual check presents several inconveniences. Firstly, this inspection of plants and vines or of the crop is imprecise and depends on the driver's experience and powers of observation. Secondly, an unacceptable proportion of unharvested grapes on the vines or of foreign bodies (leaves, stems, buds) in the harvested crop can only be detected at the end of a row. The driver cannot inspect the contents of the temporary crop storage bin whilst the machine is travelling. Moreover, he cannot see the plants which have already been harvested because they are hidden behind the machine. Furthermore, the driver has to concentrate on driving the harvester both to align with the rows of vines and to control the speed of the machine on which, among other things, the number of times the shaker units act on a vine plant depends. It therefore would be very useful to have a system which might show the driver automatically what proportion of foreign bodies there was in the grapes harvested and/or the proportion of unharvested grapes after the machine had passed.
There are some optical systems for locating fruit on trees to enable a robot to pick it.
Document FR-A-2 658 624 describes such a system in which a camera provided with photosensitive charge coupled device (CCD) elements is used to find the coordinates of a fruit in a vertical plane parallel to the row of trees from which the fruit is to be picked. A robotized picking arm is directed at substantially right angles to the vertical plane towards the point of the fruit coordinate and the arm is slowed down near to the fruit by the action of an ultrasonic detector. The image processing means comprise means for activating a flash synchronously with the camera's integration periods.
Document EP-A-0-267 860 describes another system using several multi-color cameras to detect fruit on a tree and indicate successively to a robot with a picking arm the respective positions of fruit which it detects.
Document JP-A-6 261 622 describes a similar harvesting system which uses at least two infrared wavelengths.
Such systems do not provide a solution to the problems of examining the quality of the crop and the durability of the vine which the present invention aims to resolve. Moreover, in the above systems the processing of images is especially complex because it is necessary to detect the shape and coordinates of the fruit to be picked. Detection of shape serves, in particular, to distinguish fruit from foliage if their respective colors are similar.
There are also other crop sorting systems which use a camera working in the infrared field. For example, document FR-A-2 697 450 describes a system of sorting constantly moving fruit and vegetables to separate them from others, these being made up of non-fleshy parts. This system uses infrared rays in order to detect, by means of the difference in reflectivity between the fleshy and non-fleshy parts, the presence of a non-fleshy part in or attached to the fruit.